Dual flow heat exchanger header

ABSTRACT

An A-coil heat exchanger includes a header for receiving a heat transfer fluid after the fluid has passed through the interior of the heat exchanger. The header is comprised of a main body section and first and second tubular branches depending therefrom. The first tubular branch is in fluid communication with a first coil slab of the heat exchanger by means of a first set of adapter tubes extending between the first tubular section and the first coil slab. The second tubular branch is in fluid communication with a second coil slab of the heat exchanger by means of a second set of adapter tubes extending between the second tubular branch and the second coil slab. Each of the adapter tubes defines a generally straight section of conduit between the corresponding tubular branch and the corresponding coil slab. The header is located with respect to the coil slabs such that when the heat exchanger is positioned in an air stream, the header is substantially isolated from air flowing through the first and second coil slabs.

TECHNICAL FIELD

This invention relates generally to heat exchangers used in airconditioning and refrigeration applications and in particular to heatexchangers of the A-coil type.

BACKGROUND ART

Heat exchangers are widely used in a variety of applications in thefields of air conditioning, refrigeration and the like. Typically, suchheat exchangers are comprised of plural rows of tubes in which a firstheat transfer fluid, such as water or a vapor compression refrigerant,flows while a second heat transfer fluid, such as air, is directedacross the outside of the tubes. To improve heat transfer, a pluralityof fins comprising thin sheets of metal are used. Each fin has multipleholes through which the tubes are laced and the fins are arranged inparallel, closely spaced relationship along the tubes to define multiplepaths for the second heat transfer fluid to flow across the fins andaround the tubes.

One type of heat exchanger often used in air conditioning andrefrigeration applications is the so-called “A-coil” heat exchanger, anexample of which is shown in FIG. 1. Referring now to FIG. 1, heatexchanger 10 is comprised of a pair of coil slabs 12, 14, which arecoupled together at respective ends thereof by a connector plate 16 andare in divergent relationship to define a generally “A” shape. Each slab12, 14 has plural tubes 18 laced through a plurality of fins 20. Tubes18 are adapted to allow passage of a first heat transfer fluid (e.g., avapor compression refrigerant) therethrough. Fins 20 are in parallel,closely spaced relationship and cooperate with tubes 18 to providemultiple paths for a second heat transfer fluid (e.g., air to be cooled)to flow across heat exchanger 10 on the outside of tubes 18.

Four rows of tubes 18 (two rows on each slab 12, 14) are shown in FIG.1, by way of example. In other embodiments of an A-coil heat exchanger,the number of tube rows may be greater or less than two. Each tube rowdefines a discrete fluid circuit, with each circuit comprising multiplepasses through the corresponding slab 12, 14. Return bends 22 connectdistal ends of adjacent tubes 18. Tubes 18 penetrate through end plates24 at the opposed ends of each slab 12, 14. Only one end plate 24 isshown on each slab 12, 14 in FIG. 1.

Four adapter tubes 26 connect the outlets of the respective tubecircuits to an outlet header 28 in fluid communication with the suctionside of a compressor (not shown) when heat exchanger 10 is used in avapor compression air conditioning or refrigeration system. Header 28extends horizontally across heat exchanger 10 proximate to the coupledends of slabs 12, 14, and then bends upwardly at an approximately 90°angle. Although not shown in FIG. 1, plural distributor tubes connectthe inlets of the respective tube circuits to an inlet header in fluidcommunication with the discharge side of the compressor. A drain pan(not shown) is preferably positioned under heat exchanger 10 to collectcondensate runoff.

In operation, when heat exchanger 10 is used as an evaporator, therefrigerant enters heat exchanger 10 through the distributor tubes insubstantially liquid form, makes multiple passes through heat exchanger10 in each tube circuit, is substantially vaporized in heat exchanger 10and exits heat exchanger 10 through adapter tubes 26. Further, when heatexchanger 10 is oriented in a “horizontal coil” configuration, as shownin FIG. 1, air or other fluid to be cooled flows horizontally into theregion between slabs 12, 14 and horizontally outwardly through bothslabs 12, 14, as indicated by arrows 29, whereby the air or other fluidis cooled. Header 28 is located such that the vertical portion thereofis in the air stream flowing outwardly from slab 12. Further, adaptertubes 26 are configured with multiple bends to enable adapter tubes 26to be connected to selected ones of tubes 18.

SUMMARY OF THE INVENTION

In accordance with the present invention, a heat exchanger of the A-coiltype having first and second coil slabs coupled at respective endsthereof and being in divergent relationship includes a header adapted toreceive heat transfer fluid from the slabs. The header has a mainsection and first and second tubular branches sections dependingtherefrom. The first branch is in fluid communication with the firstcoil slab and the second branch is in fluid communication with thesecond coil slab.

In accordance with one embodiment of the invention, the heat exchangerfurther includes a first conduit in fluid communication between thefirst branch and the first coil slab and a second conduit in fluidcommunication between the second branch and the second coil slab.

In accordance with another embodiment of the invention, the firstconduit defines a generally straight section of conduit between thefirst branch and the first coil slab and the second conduit defines agenerally straight section of conduit between the second branch sectionand the second coil slab.

In accordance with yet another embodiment of the invention, the firstconduit extends from the first branch in a first direction and thesecond conduit extends from the second branch in a second directionwhich is in divergent relationship to the first direction.

In accordance with still another embodiment of the invention, the headeris located with respect to the first and second coil slabs such thatwhen the heat exchanger is positioned in an air stream, the header issubstantially isolated from air flowing through the first and secondcoil slabs.

In accordance with a preferred embodiment of the invention, the heatexchanger includes plural first conduits in fluid communication betweenthe first branch and the first coil slab and plural second conduits influid communication between the second branch and the second coil slab.The first and second branches are in generally parallel relationship andextend generally parallel to an axis along which the first and secondcoil slabs are coupled.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a prior art A-coil heat exchanger;

FIG. 2 is a perspective view of an A-coil heat exchanger in accordancewith an embodiment of the present invention;

FIG. 3 is an end elevation view of the A-coil heat exchanger of FIG. 2;

FIG. 4 is a side elevation view of the A-coil heat exchanger of FIG. 2;

FIG. 5 is a top plan view of the A-coil heat exchanger of FIG. 2; and

FIG. 6 is a perspective view of a header component used in the heatexchanger of FIG. 2.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the invention will now be described withreference to the accompanying drawings. Like parts are marked in thespecification and drawings with the same respective reference numbers.In some instances, proportions may have been exaggerated in order todepict certain features of the invention.

Referring now to FIGS. 2-6, an A-coil heat exchanger 30 is comprised offirst and second coil slabs 32, 34 that are coupled together atrespective ends thereof by a connector plate 36 and are in divergentrelationship to define a generally “A” shape. Each slab 32, 34 hasplural heat transfer fluid carrying tubes 38, which are laced through aplurality of fins 40. Tubes 38 each have an internal passageway toaccommodate the flow of a first heat transfer fluid (e.g., a vaporcompression refrigerant) therethrough. Fins 40 are in parallel, closelyspaced relationship and cooperate with tubes 38 to provide multiplepaths for a second heat transfer fluid (e.g., air to be cooled) to flowacross heat exchanger 30 on the outside of tubes 38. Heat is transferredfrom the second heat transfer fluid to the first heat transfer fluid.

Four rows of tubes 38 (two rows on each slab 32,34) are shown in FIG. 1,by way of example. One skilled in the art will recognize that the numberof tube rows may be greater or less than two. Each tube row defines adiscrete fluid circuit, with each circuit comprising multiple passesthrough the corresponding slab 32, 34. Return bends 42 connect distalends of adjacent tubes 38. Tubes 38 penetrate through end plates 44 atthe opposed ends of each slab 32,34. Only one end plate 44 is shown oneach slab 32, 34 in FIG. 1.

As will be described in greater detail hereinbelow, a first pair ofadapter tubes 46 and a second pair of adapter tubes 47 connect theoutlets of the respective tube circuits to an outlet header 48 in fluidcommunication with the suction side of a compressor (not shown) whenheat exchanger 30 is used in a vapor compression air conditioning orrefrigeration system. When heat exchanger 30 is oriented for horizontalair flow, as shown in FIGS. 2-5, slabs 32, 34 are coupled together byconnector plate 36 along a vertical axis. Header 48 is positioned withrespect to the coupled ends of slabs 32, 34, such that no portion ofheader 48 would be located in a horizontal air stream flowing throughslabs 32,34. Although not shown in FIGS. 2-5, heat exchanger 30 alsoincludes plural distributor tubes connecting the inlets of therespective tube circuits to an inlet header in fluid communication withthe discharge side of the compressor. A drain pan (not shown) ispreferably positioned under heat exchanger 30 to collect condensaterunoff.

In operation, when heat exchanger 30 is used as an evaporator, therefrigerant enters heat exchanger 30 through the distributor tubes insubstantially liquid form, makes multiple passes through heat exchanger30 in each tube circuit, is substantially vaporized in heat exchanger 30and exits heat exchanger 30 through adapter tubes 46, 47. Further, whenheat exchanger 30 is oriented in a “horizontal coil” configuration, asshown in FIGS. 2-5, air or other fluid to be cooled flows horizontallyinto the region between slabs 32, 34 and horizontally outwardly throughboth slabs 32, 34, as indicated by arrows 49, whereby the air or otherfluid is cooled.

As can be best seen in FIG. 6, header 48 defines the general shape of atwo-pronged fork and is comprised of a main body section 50 and firstand second tubular branches 52, 54 depending therefrom. Branches 52, 54are in parallel relationship. Respective major axes of main body section50 and tubular branches 52, 54 are oriented along respective verticalaxes parallel to the vertical axis along which slabs 32,34 are coupledtogether. Main body section 50 has a flared open end 50 a, which isadapted to connect header 48 to a compressor suction line (not shown).An opposite end of main body section 50 is defined by a bulbous portion50 b containing first and second sockets (not shown) in which respectiveopen ends of first and second tubular branches 52,54 are received. Therespective opposite ends of tubular branches 52, 54 are closed. Firsttubular branch 52 is in fluid communication with first coil slab 32 bymeans of adapter tubes 46, which extend horizontally outwardly fromfirst tubular branch 52 along respective axes that are perpendicular tothe major axis of first tubular branch 52. Second tubular branch 54 isin fluid communication with second coil slab 34 by means of adaptertubes 47, which extend horizontally outwardly from second tubular branch54 along respective axes that are perpendicular to the major axis ofsecond tubular branch 54.

Adapter tubes 46 are in divergent relationship with respect to adaptertubes 47, corresponding to the divergent relationship between slabs 32and 34. Further, the two tubes 46 are stacked vertically one above theother and the two tubes 47 are stacked vertically one above the other,so that each adapter tube 46, 47 defines a generally straight section ofconduit between the corresponding tubular branch 52, 54 and thecorresponding coil slab 32, 34. One skilled in the art will recognizethat the aforementioned configuration of adapter tubes 46,47 eliminatesthe need for one or more bends in the adapter tubes characterized byprior art A-coil heat exchangers.

As can be best seen in FIG. 3, main body section 50 and first and secondbranches 52,54 are oriented vertically and extend generally parallel toa vertical axis along which first and second coil slabs 32, 34 arecoupled by connector plate 36. Header 48 is located with respect to coilslabs 32, 34 such that when heat exchanger 30 is positioned in ahorizontal air stream, header 48 is substantially isolated from airflowing through first and second coil slabs 32, 34.

The best mode for carrying out the invention has now been described indetail. Since changes in and modifications to the above-describedpreferred embodiment may be made without departing from the nature,spirit and scope of the invention, the invention is not to be limited tosaid details, but only by the appended claims and their equivalents.

1. In a heat exchanger having first and second coil slabs coupled atrespective ends thereof and being in diverging relationship to define anA-coil configuration, each of said slabs having at least one heattransfer carrying tube, wherein the improvement comprises a headeradapted to receive heat transfer fluid from said slabs, said headerhaving a main section and first and second branch sections dependingtherefrom, said first branch section being in fluid communication withsaid first coil slab and said second branch section being in fluidcommunication with said second coil slab.
 2. The heat exchanger of claim1 further including a first conduit in fluid communication between saidfirst branch section and said first coil slab and a second conduit influid communication between said second branch section and said secondcoil slab.
 3. The heat exchanger of claim 2 wherein said first conduitdefines a generally straight section of conduit between said firstbranch section and said first coil slab and said second conduit definesa generally straight section of conduit between said second branchsection and said second coil slab.
 4. The heat exchanger of claim 2further including plural first conduits in fluid communication betweensaid first branch section and said first coil slab and plural secondconduits in fluid communication between said second branch section andsaid second coil slab.
 5. The heat exchanger of claim 2 wherein saidfirst conduit extends from said first branch section in a firstdirection and said second conduit extends from said second branchsection in a second direction which is in divergent relationship to saidfirst direction.
 6. The heat exchanger of claim 1 wherein said first andsecond branch sections are in generally parallel relationship.
 7. Theheat exchanger of claim 6 wherein said main section and said first andsecond branch sections extend generally parallel to an axis along whichsaid first and second coil slabs are coupled.
 8. The heat exchanger ofclaim 1 wherein said heat exchanger is positionable for horizontal airflow therethrough, said main section and said first and second branchsections having respective major axes that are in parallel relationship,said respective major axes being oriented vertically when said heatexchanger is positioned for horizontal air flow therethrough.
 9. Theheat exchanger of claim 1 wherein said header is located proximate tothe coupled ends of said first and second coil slabs such that when saidheat exchanger is positioned in an air stream, said header issubstantially isolated from air flowing through said first and secondcoil slabs.
 10. A header adapted for connection to an A-coil heatexchanger to receive heat transfer fluid therefrom, said headercomprising a main section and first and second branch sections dependingtherefrom, said first branch section being adapted to receive heattransfer fluid from a first portion of the heat exchanger and saidsecond branch section being adapted to receive heat transfer fluid froma second portion of the heat exchanger.
 11. The header of claim 10further including at least one first conduit extending from said firstbranch section and being adapted to feed heat transfer fluid from thefirst portion of the heat exchanger to said first branch section, saidheader further including at least one second conduit extending from saidsecond branch section and being adapted to feed heat transfer fluid fromthe second portion of the heat exchanger to said second branch section.12. The header of claim 11 wherein said first conduit defines agenerally straight first section of conduit and said second conduitdefines a generally straight second section of conduit.
 13. The headerof claim 11 further including plural first conduits extending from saidfirst branch section and plural second conduits extending from saidsecond branch section.
 14. The header of claim 11 wherein said firstconduit extends from said first branch section in a first direction andsaid second conduit extends from said second branch section in a seconddirection which is in divergent relationship to said first direction.15. The header of claim 10 wherein said first and second branch sectionsare in generally parallel relationship.
 16. The header of claim 15wherein said main section and said first and second branch sections eachhave a major axis and a minor axis, the respective major axes of saidmain section and said first and second branch sections being ingenerally parallel relationship.
 17. In combination: a heat exchangerhaving first and second coil slabs coupled at respective ends thereofand being in diverging relationship to define an A-coil configuration,each of said slabs having a passageway adapted for heat transfer fluidto pass therethrough; and a header in fluid communication with saidslabs to receive heat transfer fluid after the fluid has passed throughsaid slabs, said header having a main body section and first and secondtubular branches depending therefrom, said first tubular branch being influid communication with said first coil slab and said second tubularbranch being in fluid communication with said second coil slab, saidheader being located proximate to the coupled ends of said first andsecond coil slabs such that when said heat exchanger is positioned in anair stream, said header is substantially isolated from air flowingthrough said first and second coil slabs.
 18. The combination of claim17 further including plural first conduits in fluid communicationbetween said first tubular branch and said first coil slab and pluralsecond conduits in fluid communication between said second tubularbranch and said second coil slab.
 19. The combination of claim 18wherein said each of first conduits defines a generally straight sectionof conduit between said first tubular branch and said first coil slaband each of said second conduits defines a generally straight section ofconduit between said second tubular branch and said second coil slab.20. The combination of claim 19 wherein said first conduits extend fromsaid first tubular branch section in respective first directions andsaid second conduits extend from said second tubular branch inrespective second directions which are in divergent relationship to saidrespective first directions.